Have 2x 12" R's that I want in 4cubes tuned to 33-34hz. Catch is that it needs to have the port in the MIDDLE between the two subs.

I designed a single box w/ 2cubes tuned to 34hz using the RE planner. I plan on just building two boxes, one reversed, with a piece of wood between the ports. Do I need to run the piece of wood all the way to the front, or just enough so the air is channeled out the port?